The present invention relates generally to integrated circuits, and more particularly, to a power supply for an integrated circuit.
Integrated circuits (IC) include power supplies that provide different supply voltages to internal circuits of the IC. ICs operate in different power modes including RUN, STOP, and STANDBY modes. The RUN mode is a high power mode and the STOP and STANDBY modes are low power modes. Power supplies further regulate the supply voltage and include a high power regulator (HPREG) for regulating the supply voltage when the IC is in the high power mode and a low power regulator (LPREG) for regulating the supply voltage when the IC is in the low power mode.
The HPREG has a high current drive and is capable of sustaining high current surges. The power consumption of the HPREG is greater than the power consumption of the LPREG and therefore, the HPREG is turned off and the LPREG is turned on to save power when the IC is in a low power mode. However, in low power modes, leakage currents are generated in the internal circuits, which may reach the order of hundreds of milli-amperes as the junction temperature of the internal circuits reaches 125-150 degrees Celsius. The LPREG is designed to sustain a low order current and often fails to sustain an increased current requirement of the order of milli-amperes and causes the IC to reset. The LPREG further causes the IC to reset when transient load currents and DC load currents become unexpectedly high when the IC transitions from the RUN mode to the STOP mode.
The IC is rebooted in the event of a reset, which affects the system state and leads to loss of critical data and time. In systems such as automotive systems, system state is critical and it is preferable not to lose system state due to frequent resets.
One solution to tackle the above-mentioned problem is to design the LPREG such that it sustains the increased leakage current and high transient currents. However, it is difficult to predict total leakage current and transient currents, especially in automotive systems, where temperature variations are quite high and the leakage currents fluctuate with temperature variations. Even if an LPREG is designed using estimated leakage and transient currents, there is no fall back option available to prevent the IC from a reset and reboot caused by reasons other than leakage or transient currents.
Hence, there is a need for a power supply that efficiently regulates supply voltage, prevents an IC from a reset caused by leakage and transient currents, and overcomes the above-mentioned limitations of existing power supplies.